Numerous lift assemblies have been designed for attachment to vehicles and most commonly to facilitate loading and unloading from a truck tailgate. Many of the prior art tailgate lift assemblies require integration into the side wall or bed of the vehicle in order to adequately support the lift assembly and weighted load. Powerful hydraulics or lift drives are also required for many of these lift assemblies, if the lifts are intended to be used with substantial loads.
The integration of lift assembly mounts into the side rail or bed of a vehicle is difficult and expensive, both in time and material. Devices have been provided where a mechanism for a tailgate lift utilizes cables, such as in U.S. Pat. No. 4,601,485, screw drives as shown in U.S. Pat. No. 3,180,503; and power from a winch mounted on the vehicle as shown in U.S. Pat. No. 6,609,481.
Some devices have even been designed to mount on a trailer hitch as in U.S. Publication No. 2007/0280807 disclosing a carrier with a screw drive to adjust the height, and U.S. Publication No. 2001/0014272 disclosing a lift connected to its hitch mounted yoke by pairs of parallel support bars. However, this latter publication is inoperable in practice because the lift is allowed to pivot so that the support bars extend both upward and downward from the yoke, causing a situation that requires vertical force to raise and lower the lift.
These and other devices of the prior art fail to be easily integrated with presently existing vehicles and require extensive engineering and manufacturing to mount and operate effectively.
In the prior art there does not exist a simplified unit for providing a vehicle mounted lift assembly, that can be hitch mounted, and providing mechanical advantage so that loads may be lifted manually or with relatively small motors contained within the lift assembly.